A risk factor is something that increases your chances of developing cancer.

It is possible to develop stomach cancer with or without the risk factors listed below. However, the more risk factors you have, the greater your likelihood of developing stomach cancer. If you have a number of risk factors, ask your doctor what you can do to reduce your risk.

There are a number of risk factors for the development of stomach cancer. Many of the risk factors involve decreased levels of acid in the stomach—conditions that affect the amount of stomach acid produced seem to increase the risk of stomach cancer.

Researchers would like to understand more about the risk factors for stomach cancer. For example, there is a much higher risk of stomach cancer among people living in Japan. No one is sure what causes this increased risk. Some researchers think the increased risk may be related to an environmental exposure occurring in early childhood.

The major risk factors for stomach cancer include the following:

Cigarette Smoking

Cigarette smoking is known to increase the risk of developing cancer in the part of the stomach closest to the esophagus.

Helicobacter pylori
(
H. pylori
) Infection

H. pylori
is a type of bacteria known to cause stomach ulcers and chronic inflammation of the lining of the stomach. Although it appears that a large percentage of people with stomach cancer have
H. pylori
infection, the majority of people with this type of infection don’t go on to develop stomach cancer. Still, it’s important not to ignore symptoms of
ulcers
or stomach inflammation.
H. pylori
can be effectively treated with antibiotics, and it is important to do so to decrease your risk of developing stomach cancer.

Chronic Atrophic
Gastritis

With
gastritis
, the stomach has fewer glands than normal, resulting in chronic inflammation in the stomach and decreased acid production, both of which can increase your risk of stomach cancer.

Barrett's Esophagitis

Barrett's esophagitis is considered on of the risk factors. It is an abnormal change (metaplasia) in the cells of the lower end of the esophagus. The change is thought to be caused by damage from chronic acid exposure, or reflux esophagitis. The normal lining of the esophagus (squamous epithelium) is replaced by an intestinal-type lining (columnar epithelium).

Dietary Factors

People who eat a large amount of foods that are preserved with nitrates, nitrites, and other substances (eg, smoked, salted, or pickled foods) have a higher risk of developing stomach cancer.

As with other forms of cancer, certain foods appear to be protective against stomach cancer. For example, people whose diets are high in fiber and vegetables may have a lower risk of developing this form of cancer. Specifically, allium vegetables (eg, onions, garlic, shallots, leeks, chives) may offer some protective benefits.

Alcohol Use

Heavy alcohol use may increase the risk of developing cancer in the part of the stomach closest to the esophagus.

Occupational Exposures

You may have a higher risk of stomach cancer if you work in a job, such as a mechanic or contractor, which exposes you to high levels of heavy metals, rubber, or asbestos.

Family History

Your risk of developing stomach cancer is increased if others in your family have had stomach cancer. You are also at higher risk if your family has a history of hereditary nonpolyposis colon cancer (Lynch Syndrome or HNPCC), familial adenomatous polyposis, or the inherited breast cancer genes, BRCA1 and BRCA2.

History of Stomach Surgery

You have an increasing risk of developing stomach cancer starting at about 15 years after having had stomach surgery, such as a partial gastrectomy (removal of part of the stomach) and vagotomy (surgery involving the vagus nerve).

History of Stomach Polyps

Polyps are benign fleshy growths that may occur on the lining of the stomach. Your risk of stomach cancer is increased if you have the kind of polyp known as an “adenomatous polyp.” Other kinds of stomach polyps don’t increase your risk.

Pernicious Anemia

People with
pernicious anemia
have a higher risk of developing stomach cancer. Pernicious anemia, also called megaloblastic anemia, is a rare disorder in which the body does not absorb enough vitamin B12
from the digestive tract, leading to decreased production of red blood cells (RBCs). Pernicious anemia is caused by a lack of a substance called intrinsic factor, which is normally in the digestive tract and is essential for the absorption of vitamin B12
from food.

Age

People over the age of 50 have an increased risk of stomach cancer. The average age at diagnosis is between 60 and 70 years of age.

Race

People of Hispanic, Asian, or African origin have a considerably greater risk of developing stomach cancer.

Gender

Men are about twice as likely as women to develop stomach cancer.

Blood Type

People with type A blood have an increased risk of developing stomach cancer. Researchers are still trying to understand why.

Revision Information

This content is reviewed regularly and is updated when new and relevant evidence is made available. This information is neither intended nor implied to be a substitute for professional medical advice. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with questions regarding a medical condition.